The invention relates generally to numerical encoding devices for electronic circuits, and, in particular, to a setting ring system of a electronic artillery fuze for sensing the angular position of a setting ring and converting it into a digital electrical signal indicative of that position.
Several types of fuzes used on artillery ammunition require the setting of an event time prior to firing. The fuze setting time system must be a rugged, compact system, at which the time value can be accurately set and displayed, without the use of tools or electric power. In the past, this has often been done by turning the fuze nose relative to marks on the fuze body.
U.S. Pat. No. 4,594,944, issued June 17, 1986 to Rongus et al., discloses a system for setting a timing value of an electronic fuze which utilizes two adjacent setting rings disposed about the outside of the fuze housing. These setting rings are interconnected with the housing so that one ring rotates with the other ring when the other ring is manually rotated in one direction about the housing axis, but is prevented from rotating when the other ring is rotated in the opposite direction. Each ring carries a plurality of numbers disposed about its outer periphery such that one of the numbers is axially aligned with an indication mark on the fuze housing at each setting of the ring. The two series of numbers are oriented laterally such that the two numbers aligned with the indication mark constitute the desired timing value. Each setting ring activates a ring-type membrane switch assembly disposed between the ring and the fuze housing to encode a multi-bit code to the electronic fuze corresponding to the indicated number of that ring.
All of the known systems for manually setting a timing value of an electronic artillery fuze utilize a plurality of mechanical switches which are opened or closed in accordance with the angular position of the setting ring associated with the switches to determine the digital signal encoded to the fuze at the time of firing. During long periods of storage, the contacts of the mechanical switches are subject to corrosion. Thus, it would be highly desirable if the encoding mechanism did not included any moving contacts subject to such corrosion.